1. Field of the Invention
The present invention relates generally to medical and surgical devices, and more specifically to trocar assemblies.
2. Description of Prior Art and Related Information
Trocar assemblies, or simply trocars, are generally used in minimally invasive surgeries such as laparoscopy. Such procedures require that any instrumentation inserted through a trocar assembly into the body be sealed in order to prevent gases from entering or exiting the body, such as in the case of a laparoscopic surgery where the accessed abdominal cavity has been insufflated.
The need to provide a tight seal is countered by several other demands, including the need to accommodate instruments of varying sizes as well as the need to allow for movement of the instrument within the trocar assembly. In an effort to fulfill these competing requirements, attempts have been made to provide a universal seal composed of a single material with a single orifice that can be adjusted to accommodate instruments of different sizes.
A material that works well for a small instrument, however, might not be suitable for a large instrument. Attempting to accommodate both a small instrument and a large instrument with a single seal is especially difficult given the fact that a small instrument has a greater range of lateral, or side-to-side, movement than a large instrument. If the material is too compliant, the seal will leak with a small instrument due to the wide range of lateral movement. If the material is less compliant, the force required to dilate the seal in order to accommodate large instruments may be too great. Such a dilemma is only one of several involved attempting to provide a single, universal seal in a trocar.
Even if a single universal seal could be dilated in order to accommodate both large and small instruments, trocars which must be dilated present another obvious problem. In a typical laparoscopic surgery, a “free hand” is seldom available to manually adjust the trocar. Yet, several attempts have been made to provide adjusting mechanisms which would require manual manipulation.
Thus, the varying diameters of different sized instruments, the varying side-to-side motion of different instruments, and the lack of a free hand for manual adjustment all contribute to the difficulty of providing an effective and convenient trocar.